diff --git a/CHANGELOG.md b/CHANGELOG.md
index b442ce5..2dc35d6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- **`uvicorn` is capped below 1.0** (`pyproject.toml`). It was floor-only
+  (`>=0.23.0`), and jvspatial is the package that actually drives it —
+  `api/server_run.py` calls `uvicorn.run` with a config dict, so a major
+  release is free to rename or drop the kwargs passed there. In practice the
+  open spec let a resolver move an existing environment from 0.44 to 0.52
+  between two installs of the same commit, silently. The cap keeps resolution
+  inside a range that has been tested without pinning consumers to an exact
+  version.
+
 ## [0.0.17] - 2026-08-05
 
 ### Fixed
diff --git a/pyproject.toml b/pyproject.toml
index 3afec50..44715a5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -35,7 +35,12 @@ dependencies = [
     # lifespan), not the Router(on_startup/on_shutdown) API that 1.0 removed, and
     # route introspection is version-agnostic via _route_utils.iter_api_routes.
     "starlette>=0.46.0",
-    "uvicorn>=0.23.0",
+    # Capped below 1.0: uvicorn is the ASGI server jvspatial actually drives
+    # (api/server_run.py calls uvicorn.run directly with a config dict), so a
+    # major release is free to rename or drop the kwargs we pass. The floor-only
+    # spec let a resolver walk 0.44 -> 0.52 unnoticed between two installs of
+    # the same commit; a cap keeps that inside a range we have tested.
+    "uvicorn>=0.23.0,<1.0.0",
     "python-multipart>=0.0.6",
     "motor>=3.0.0",
     "pymongo>=4.0.0",